1. Technical Field
The present invention relates to a printer for printing in accordance with a print instruction from a print instruction terminal such as a personal computer (PC) and, more particularly, it relates to a printer that stores a plurality of print material data to provide the material data for printing, a print instruction terminal, a printing system, a printing program, and a printing method therefore.
2. Background Art
Since document data created by print instruction terminals are not generally printed by printers if not processed, they are printed after being converted to raster image data in which dot-by-dot color information such as Bit MaP are enumerated.
The conversion process from document data to raster image data is generally referred to as rendering. With general inkjet printers, the conversion process is performed by a printer driver incorporated in a print instruction terminal on the side of the print instruction terminal. With general laser printers, it is performed on the side of a printer after document data is temporarily converted to a small-size intermediate language such as a page description language (PDL) on the side of a print instruction terminal.
Rendering requires a vast amount of information processing, posing the disadvantage of taking a long time after a user provides a print instruction on the side of the print instruction terminal until printing is actually started. The disadvantage appears remarkable particularly for print data with a high data volume, such as a color image, and for a print instruction terminal and a printer itself with low information processing power.
In order to increase the speed of a printing process, for example, printing methods referred to as “overlay printing” and “business form printing” have been proposed, as shown in JP-A-9-39312.
The printing method referred to as “overlay printing” is as follows. Material data that is frequently used in printing, such as a company name, rule lines, and a logo mark, is stored in a printer in advance and, at the time of printing using the material data, printing is performed using the material data stored in the printer merely by providing a print instruction to designate the material data, thereby reducing the amount of data transferred of the entire document to be actually printed to advance the printing start time, thus increasing printing speed. The printing method that is referred to as “overlay printing” remarkably offers the above advantage particularly for material data with a high data volume such as a color image.
In order to store material data on the side of a printer, it is necessary to provide a storage device only for material data, such as a semiconductor memory and a hard disk drive (HDD), in the printer. The storage devices are however limited in storage capacity. Accordingly, it is desirable not to store the material data in an unprocessed form but to store it after reducing its size using data compression techniques such as ZIP and Joint Photographic Experts Group (JPEG).
When raster image data or PDL is sent to a printer after being compressed on the side of a print instruction terminal, a data transfer amount is reduced, allowing high-speed printing.
However, in order to practically use the material data compressed and stored or the material data compressed and transferred in that way as print data on the side of a printer, it is necessary to temporarily and completely restore (hereinafter, referred to as “decompress” as appropriate) the compressed and stored material data to its original size on the side of the printer. The data decompressing (also referred to as expanding or unarchiving) process generally takes a long time, resulting in decreasing by half the advantages of high-speed printing and efficient storage due to the reduction in the amount of data transferred.
When the decompressed material data is stored without being processed, the storage capacity of a storage device gets is quickly consumed. It is therefore desirable to store it after recompression. However, this requires wasteful processing for material data that may be used frequently.
With irreversible compressed data as in JPEG which is a standard static-image compression technology, the repetition of compression will cause data loss to degrade image quality. It is therefore unfavorable to repeat compression.
Accordingly, the present invention has been made to effectively solve the above problems. It is an object of the invention to provide a new printer achieving high-speed printing and a print instruction terminal, a printing system, a printing program, and a printing method for the same.
It is another object of the invention to provide a new printer and a print instruction terminal capable of realizing the optimum data manipulation according to the frequency of use and character of the material data, and a printing system, a printing program, and a printing method of the same.